The mechanism of transport of proteins into mitochondria of yeast is being studied. In particular, experiments will be carried out to determine whether the mechanism of transport is predominantly post-translational or co-translational. This will be approached kinetically whereby the rates of transport using an in vitro protein synthesizing system and isolated, intact mitochondria will be used. These experiments are designed to test the role of ribosomes bound to the outer mitochondrial membrane in yeast and to determine if these bound ribosomes offer a kinetic advantage to the transport process.